Sinker cam mechanism for circular knitting machines and method of operating a circular knitting machine



Nov. 7, 1950 529,181

F. R. PAGE 2, SINKER CAM MECHANISM FOR CIRCULAR KNITTING MACHINES ANDMETHOD OF OPERATING A CIRCULAR KNITTING MACHINE Filed April 25, 1947 5Sheets-Sheet 1 Nov. 7, 1950 F. R. PAGE 2,529,181

. SINKER CAM MECHANISM FOR CIRCULAR KNITTING MACHINES AND METHOD OFOPERATING A CIRCULAR KNITTING MACHINE Filed April 25, 1947 3Sheets-Sheet 2 T F- C 306 fnven'z'ar FRANK R. PAGE 2 his ai-Z-arne yiNov. 7, 1950 F. R. PAGE 2,529,181

SINKER CAM MECHANISM FOR CIRCULAR KNITTING MACHINES AND METHOD OFOPERATING A CIRCULAR KNITTING MACHINE Filed April 25, 1947 3Sheets-Sheet 3 In-ueniar FRANK R. PAGE Q hzLs'aZZ-arnqya MMJM PatentedNov. 7, 1950 SINKER CAM MECHANISM FOR CIRCULAR KNITTING' MACHINES ANDMETHOD OF OPERATING A CIRCULAR KNITTING MA- CHINE Frank R. Page,Laconia, N. H., assignor to Scott- & Williams, Incorporated, Laconia, N.IL, a corporation of Massachusetts Application April 25, 1947, SerialNo. 743,870

9 Claims. (61.66-108) This invention relates to sinker cam mechanism forcircular knitting machines and more particularly to machines adapted tomake finegauge hosiery. In modern hosiery for ladies it is necessary tomake time stitches, and yet at certain parts of the stocking such as themakeup and picot it is necessary to have stitches which are considerablyslacker than the tight stitches. It is known to box in the sinkers atthe knocking-over point on circular knitting machines in order toproduce small stitches, but no satisfactory way has heretofore beenevolved for making uniform stitches and at the same time obtainingaccurate casting off of slack stitches. I have discovered how this canbe accomplished, and it is characteristic of my invention that thesinkers are boxed in at the castoff point and that when making slackstitches the sinkers are holding the fabric down at an auxiliary pointby resilient pressure. This is accomplished by the use of two cast-offcams, the first being a fixed one with the sinkers controlled by anadjustable boxing-in or landing cam, and the second .or auxiliarycast-off cam located at a point shortly after the regular castoff pointbeing pressed radially inward by spring pressure. It is alsocharacteristic of my invention when used for certain purposes that thespring pressure is varied at different parts of the knitting of astocking.

In the drawings:

Figure l is a perspective view of the essential parts of the mechanismfor exerting spring pressure on the auxiliary cast-off cam;

Figure 2 is a plan-view of the outer sinker cap of a machine made inaccordance with my invention, showing the cams which operate on thesinkers as they near the knocking-over point;

Figure 3 is a side elevation of a needle and sinker in the machine ofFigs. 1 and 2, showing the sinker, needle and stitch relation at theregular sinker cast-off point when the sinker is controlled by acombination of the regular cast-off cam and boxing-in cams, inaccordance with my invention;

Figure 4 is a view similar to Fig. 3 showing the relation of the needleand sinker of Fig. 3 with the yarn omitted;

Figure 5 is a View similar'to Fig; 3 but showing the sinker inserted tofull depth by the auxiliary sinker cam to cast off a loose stitch;

Figure 6 is a view similar to Fig. 3 showinga loose stitch when there isno auxiliary cast-off cam;

sinkers of Fig. 7 with the cam surfaces in dotted lines; while M Figure9 is a diagrammatic view in elevation of the knitting cams at theknocking-over point of the embodiment of Figs. 1 to 8.

The ordinary modern circular hosiery machine with independent needles Nand sinkers 292 for making hosiery contains a circle of sinkers actingas webholders which" are actuated by cams in the usual outside sinkercap 300. The sinkers face inwardly and have nebs 290 above knocking-overledges 29L These sinkers are adapted to assist in holding downnewly-drawn stitches while the needles N are rising after passing underthe point of the stitch cam 360 (Fig. 9). Ordinarily the insertion ofthe sinkers at the knocking-over point comes to its maximum at the linemarked A in Fig. 9, the position of this maximum insertion also beingindicated with relation to the sinker wave in Fig. 8. This insertion isordinarily caused by what is known as the cast-01f cam, which I willhereinafter designate as the regular cast-off cam 308. The sinkers aredriven in by it until they exert pressure on the newly-formed loops.However, I have found that it is impossible to control all sizes andtypes of stitches properly by this one cam 308 when knitting a completefine-gauge stocking. When the regular cast-off cam is used alone thesinkers are free to continue their inward movement until they hit thefabric. When the sinkers are operated in this manner they fire inwardand help to cast off the loose stitches. On the other hand, their actionmay be irregular and, furthermore, is much affected by the speed of themachine. Thus at high speed a slacker fabric is knit than at a lowspeed. This is particularly noticeable when the machine slows down justbefore changing into the heel. At this point one or more very tightcourses occur and there may even be cutting of the yarn due to thetightness of the stitches. To get uniform stitches regardless of thespeed of the machine, I box the sinkers in at the regular sinkercast-off point A. The end or tip 3l0 of the regular center sinker cam3|2 therefore is made pivoted and is held in adjusted position by ascrew 3 to box in the sinker butts so they cannot drive in. It acts as alanding cam. On the other hand, it is extremely difficult with thesinkers boxed in to hold the stitches down for casting off during themake-up courses and the 492 onthe latch ring post (not shown) I havealso found it possible by using spring pressure at the auxiliary sinkercast-off point C, in distinction to the boxed-in arrangement at theregular sinker cast-off point A, to vary the pressure at point C inaccordance with the needs of the various parts of the stocking. Thus,.for example, too great a pressure on the auxiliary sinker cast-off camwill cause cutting of the yarns in the make-up, but considerablepressure is necessary on the auxiliary cam when casting'off tuckstitches used in making a picot. Some pressure is also'desirable in therest of the welt. I

therefore not only provide means for putting ,spring pressure on theauxiliary sinker cast-off cam when needed, but also make such pressurevariable.

The mechanism for controlling the auxiliary sinker cast-off cam in thismanner is controlled from the main pattern drum by means of drum camsSM, 502, 503 which, respectively, are

shown as high, medium and low drum cams (Fig. 1). They are all in thesame path on the drum and serve to move a thrust bar 431. v This thrustbar can be used to actuate the latch closing ring (not shown), all asset forth in the patent to Robert W. Scott No. 1,238,052, dated August21, 1917, for Yarn Feeding Mechanism for Knitting Machines. The upperend of the thrust bar is connected to the lower arm of a bell cranklever 493 which oscillates about a stud The upper arm of the bell cranklever is connected to a wire 618 going to the latch closing ring abovementioned. The control of the auxiliary sinker cast-ofi cam 309 isobtained from the upper arm of the bell crank lever 493 as follows.There is the usual tension spring 414 attached between the upper arm ofthe bell crank lever 493 and the latch ring 55.0 to press the upper armagainst the means operating the auxiliary cast-off cam 309. Mounted onthe bedplate B of the machine is a post 324 which supports a verticalrod 325 by means of two lugs 323 forming part of the post.

'On the upper end of the rod is fastened an arm 32'! lying in the pathof the upper arm of the bell crank lever 493. The lower the thrust rod,the more the bell crank lever pushes against the arm 32-? and turns thevertical rod 325. The rotation of the vertical rod 325 is transmitted tothe auxiliary sinker cast-off cam 309 by means of a sinker slackeninglever 328j attached to the rod 325 and a leaf'spring 329 on that lever.As can be seen in Fig. 1, the lever crosses under the upper of the twolugs 32 3, and the leaf spring 329 lies just outside the auxiliarycast-off cam 309. There is a tension spring 330 tending .to turn thelever 328 away from the auxiliary cam 309 against the pressure oftension spring 4'54. The angle of the arm 32% and the spring 329 is suchthat the spring is out of contact with the auxiliary cast-off cam,except when the thrust rod is on the low drum cam 503 or directly on the4 the tension spring 330 attached to the vertical rod 325. This operatesagainst the drum cams 502, 503. When it is on a low pattern drum cam503, it exerts a moderate amount of pressure against the cam, such as issuitable for use during the makeup. When the, thrust rod is lowered tothe surface of the pattern drum the rod 325 is turned further by thebell crank lever 493 and the pressure is increased to that necessary forthe picot cast-01f. It will be noted that the high drum cam 50| servesto actuate the latch opening ring and that this actuation occurs at atime which does not interfere with the insertions of the auxiliarysinker cast-off cam.

With the arrangement described it will be seen that the sinkers arepositioned accurately at the regular cast-off point and that theiroverthrow is prevented by the boxed-in cams. At the same time thearrangement of the parts is such that the sinkers press inwardly byspring pressure at the auxiliary cast-01f point when stitches are beingmade which require greater pressurefor casting off than canlbe obtainedfrom the boxedin cams.

In this way the diificulties of both boxed-in cams-and of thespring-pressed regular sinker cam are avoided. The tight line across thein step of the stocking that, tends tov be formed by the lack ofoverthrow of the sinkers when the machine is slowed down prior tostarting the heel or at any other time when: the machine is slowed downor stopped, is eliminated. Also, vertical streaks caused by uneventightness of the sinkers in their slots are avoided. On the other hand,all the stitches are cast off clean.

The operation of the machine will now be described. Assuming that themachine is about to commence the manufacture of a stocking beginningfrom the bare needles, the parts will be pattern drum itself. The leafspring 329 is held away from the auxiliary cast-off cam 309 by in theposition of Fig. 1. Then the pattern. drum is racked to bring a low drumcam 503 under the thrust rod 46!. When the thrust rod drops onto thislow cam, the bell crank lever 493 pushes the arm 32'! against thetension spring 330 so as to bring the leaf spring.329 against theauxiliary.

cast-off cam 309 with light. pressure. Thislight pressurev by thesinkerslackening cam 328 and the leaf spring 329 is maintained duringthe make-up courses. It. insures that the sinker nebs 290 get over thestitches and hold them down. At the commencement of. the welt thepattern drum is racked again until the'thrust rod drops down onto thesurface of the pattern drum I20 itself; This causes the sinker slack;-ening lever 328 to put heavy pressure on the auxiliary sinker cam duringthe welt. This insures that there is sufficient pressure to cast off thepicot tuck stitches in the welt. The position of a sinker is shown inFig. 5. This full pressure against the sinkers at the auxiliary cast-offline C is relieved as soon as the welt has been completed and theknitting of the stitches in the leg begins. For this purpose the mainpattern drum is racked to bring av medium drum cam 502 under the thrustrod. Thereupon the tension spring 330 swings the leaf spring 329 awayfrom the auxiliary sinker cast-off cam to the position shown-in Fig. 1.In this figure the pattern drum I20 has been turned fromits positionduring the leg in order to show the drum cams. The thrust rod is at thesame elevation as during the leg, although actually during the leg itwould be resting on the other drum, cam marked 502. The parts normallystay in thi's position throughout the knitting of the leg, the

drum being racked forward to bring a high drum cam 50l under the thrustrod during the reciprocatory knitting of the heel and toe. However,under certain conditions it has been found advantageous to have thethrust rod 46! rest on a cam of the height equal to drum cam 503 duringthe making of the leg and foot. This results in the auxiliary cam 309exerting a light pressure on the stitches after they have been cast offin the leg and gives an evening effect to the stitches. It is during theheel and toe that the gap closing ring is brought into operation. Itwill be observed that there is no necessity for extra pressure on thesinker at this time in order to obtain proper casting off. It will alsobeobserved that while the amount of projection of the sinkers at theauxiliary point C is limited by the fabric, the projection at theregular point A is determined by the cams in the raceway.

What I claim is:

1. In a circular knitting machine having independent latch needles andsinkers, control means for the sinkers comprising a cam at the cast-01fpoint to press the sinkers in and an adjustable cam opposite it boxingthe sinkers in at that point to prevent overthrow, in combination with amovable secondary cast-01f cam following and spaced from the cast-offpoint to push all the sinkers in an extra depth, and resilient meansadapted to press the secondary cam inwardly, for the purpose described.

2. In a circular knitting machine having independent latch needles andsinkers, control means for the sinkers comprising a cam at the cast-offpoint to press the sinkers in and an adjustable cam opposite it boxingthe sinkers in at that point to prevent overthrow, and a movablesecondary cast-off cam following and spaced from the cast-off point, incombination with a spring adapted to press the secondary cam inwardlyand control mechanism for the spring adapted to vary the pressure on thesecondary cast-off cam according to the stitch being knit.

3. In a circular knitting machine according to claim 2, a pattern drumand cams of different heights on said drum, in combination with leversfrom said pattern drum to said spring adapted to vary the pressure ofthe spring on the secondary cast-0E cam in accordance with the heightsof the drum cams.

4. In a circular knitting machine according to claim 3, the adjustmentof the levers such that with one height of drum cam, pressure of thespring on the secondary cast-oif cam is entirely relieved.

5. In a circular knitting machine having independent latch needles and aseries of sinkers, a stationary center landing cam adjusted to limitsinkers at the cast-off point to give uniform movement, and a cast-offcam pressing the butts of sinkers against that landing cam, in combi- 6nation with a movable secondary cast-off cam following and spaced fromthe cast-ofi point adapted to move sinkers further toward the center ofthe machine than permitted at the cast-- off point, and spring meanspressing this secondary cast-off cam inwardly against the sinkers.

6. In a method of operating a circular knitting machine havingindependent latch needles and sinkers, the steps of guiding the sinkersin a boxed-in path at the sinker cast-01f point so as to preventoverthrow, in combination with the step of pushing the sinkers radiallyinward under resilient pressure at a point shortly after the castoffpoint to hold down stitches.

7. In a method according to claim 6 of operating a circular knittingmachine having independent latch needles, sinkers, a landing cam and aregular cast-off cam, the step of holding down tight stitches at thecast-off point by means of the landing cam and regular cast-off cam, incombination with the step of exerting spring pressure at a pointfollowing the cast-off point to hold down slacker stitches by springpressure.

8. A method of operating a circular knitting machine to make a stockingcontaining an inturned welt started with make-up stitches and an anklecontaining tight stitches, comprising the step of guiding sinkers in aboxed-in path at the cast-off point to prevent varying pressure againstthe tight stitches, in combination with the step of pushing the sinkersinward under resilient pressure against the make-up stitches at a pointshortly after the cast-off point to hold down said make-up stitches.

9. A method of operating a circular knitting machine to make a stockingcontaining a picot formed with tuck stitches and an ankle containingtight stitches, comprising the step of guiding the sinkers in a boxed-inpath at thecast-off point to prevent varying pressure against the tightstitches, in combination with the step of pushing the sinkers inwardunder firm spring pressure at a point shortly after the cast-01f pointto cast off said tuck stitches.

FRANK R. PAGE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,641,554 Scott Sept. 6, 19272,063,026 Bristow Dec. 8, 1936 2,142,693 Lawson et al Jan. 3, 19392,200,207 Page et a1. May 7, 1940 2,337,153 Cloutier Dec. 21, 1943FOREIGN PATENTS Number Country Date 221,686 Great Britain Sept. 18, 1924

